help 'tricking' a light sensor. What is this sensor? for car auto headlights

Thread Starter


Joined Jan 21, 2016
hi all:

I need some help identifying some light sensors.
I want to 'trick' my car into thinking it's always dark out so the auto-headlights stay ON all the time. If i simply leave the switch in the ON position, the headlights will stay on all the time as i desire, but if i forget to switch it off before exiting the car, the headlights will stay on all day and drain my battery. ONLY when the switch is in the AUTO position will the headlights turn off when i turn the car off.

My goal was to find the light sensor and simply cover it with black paint or something. But unfortunately, the auto-headlight ambient light sensor is BUILT-IN with the auto-windshield wiper sensor adhered to the windshield. I took it apart figuring i would find two separate sensors (one for headlights and one for wipers), but i can't tell what controls what. If i cover the entire part, i achieve my desired results for headlights, but the car thinks it's always raining out.

Here's what the sensor looks like from the outside.

I took the sensor apart but didn't take an actual picture of the circuit board before putting it back together. But i 'remember' what it looked like, somewhat. I made this quick diagram to show the main components on the board. These are NOT actual pictures, they're from memory.

So here's what i need help with. What are all of these components?

I know how the auto-wipers system works. The two infrared LEDs shine light at an angle towards the windshield. With no rain on the glass, all of the light shines back onto the light sensors. When rain is on the glass, some of the light is sent out in different directions and less light makes it back to the sensors.

Can you tell which components control the auto-wipers and which ones control day/night for the headlights? Could it be that the same sensors that sense rain also sense ambient light?

Thanks for the help!!



Joined Sep 7, 2013
Just leave your headlights on at all time. People that forget to put their headlights on when it gets dark already have a long list of excuses.


Joined Sep 7, 2013
This was not meant as a disrespect. I live in a country where in the darkest month we get like 3-4 hours of sunlight if there are blue skies and in the summertime there is nothing that could be called night. After some thought and anecdote we decided that you should be at all times have your headlights on. Because when it comes to the individual to choose they will always find some excuses for not having their headlights on.

Hope that cleared my view up a bit. ;)


Joined Nov 24, 2012
Doesn't your car have a dinger that reminds you when you leave the lights on.
If you lived in Canada your issue would be solved, all Canadian cars require day time running lights.
Do what some of the high end car manufactures did. Add a row of LEDs inside the headlight housings that go on and off with the key.